While the death toll of soldiers in Iraq and Afghanistan receives daily attention, another type of casualty goes less noticed. A new U.S. Army study finds that, as in previous wars, soldiers in Iraq are paying an emotional price for the fighting.

The study of 6,000 U.S. soldiers shows that nearly one out of every five returning from Iraqi combat experiences anxiety, depression, or post-traumatic stress disorder. That is almost twice the pre-deployment rate.

In Afghanistan, where fighting is less fierce, the study finds that mental health problems are less prevalent, not much higher than the pre-deployment rate. American soldiers in Iraq are much more likely than those in Afghanistan to have been attacked, injured, or have killed or injured people in combat.

Army psychologist Lieutenant Colonel Carl Castro says that troops' emotional suffering is proportional to the amount of combat they see, and not necessarily related to the war's political context.

"The combat experiences are one of the key predictors of the development of signs or symptoms of post-traumatic stress disorder,? Colonel Castro said. ?The difference between the Iraqi population and the Afghanistan population is simply the difference between the types of combat experiences they encountered."

Colonel Castro says his paper is the first to compare the state of American soldiers' mental health before entering combat and so quickly after they return.

"We have never conducted a study like this,? Colonel Castro said. ?These results are the clearest most precise understanding we have of the level and type of mental health concerns experienced by our combat troops before, during, and following combat. We see the combat effect on the individual's perceived and actual mental health."

Colonel Castro says that the mental health status of today's soldiers is similar to that of previous wars. But because this study looks at soldiers so much earlier than studies on past wars did, he says it's still too soon to make a direct comparison.

In Boston, psychiatrist Jonathan Shay, who specializes in combat-traumatized military veterans, hopes the U.S. Army will gather more information.

"I hope that they will follow the people that they have looked at over time, and follow them after they leave the service. Because that's a part of it where data are really needed," Mr. Shay said.

The research, appearing in the New England Journal of Medicine, suggests that the U.S. military must continue to fight the stigma attached to mental health. It shows that those who have a psychiatric problem are about twice as likely to avoid seeking help, thinking it means they are weak or they would be penalized.

Colonel Castro explains that the military is doing more mental health care in the field, and also hopes to make psychological screening part of a soldier's routine physical exam.